1. Field of the Invention
The present invention relates to an apparatus for producing a metal formed product, which is used in order to obtain a predetermined metal formed product from semisolidified metal.
2. Description of the Related Art
In general, an operation is performed, in which molten metal composed of, for example, aluminum, magnesium, or alloy of each of them is used to produce semisolidified metal, i.e., slurry in an amount of one shot for the forming process. It is known that the forming operation based on the use of the slurry is advantageous especially in that the surface accuracy and the internal quality of a formed product are excellent.
For example, a method has been suggested, in which slurried semisolidified metal is obtained by rotating a chiller cooled to have a temperature of not more than a temperature of molten metal, in the molten metal supplied to a heat-insulating crucible (vessel), and then the semisolidified metal is introduced from the heat-insulating crucible to a forming machine to apply a forming treatment so that a metal formed product having a predetermined shape is produced (see Japanese Laid-Open Patent Publication No. 11-197814).
In the case of the conventional technique described above, it is necessary to remove solidified matters adhered to the chiller, for example, aluminum solidified matters, after the semisolidified metal is obtained in accordance with the rotating action of the chiller in the heat-insulating crucible. Therefore, the chiller is usually removed from a rotary shaft, and the chiller is set to a restoring apparatus so that a predetermined restoring treatment is applied to the chiller by the aid of the restoring apparatus.
In this case, when the operation to apply an agitation treatment to the molten metal supplied to the heat-insulating crucible is completed, it is necessary that the chiller is installed to the restoring apparatus to apply the restoring treatment thereto. Therefore, it is required that the operation to exchange the chiller between the agitation apparatus and the restoring apparatus is frequently performed during the forming operation steps. The following problem is pointed out. That is, a considerable period of time is required for the restoring treatment for the chiller. The entire steps for producing the metal formed product are not efficiently performed.
In the conventional technique described above, when the semisolidified metal is introduced into the forming machine after the semisolidified metal is formed in accordance with the rotating action of the chiller in the heat-insulating crucible, it is necessary to apply a predetermined restoring treatment to the heat-insulating crucible before the next time forming operation is performed for another semisolidified metal. Specifically, the following treatments are performed, i.e., a treatment for removing solidified matters, for example, aluminum solidified matters adhered to the inner wall surface of the heat-insulating crucible, a treatment for adjusting the heat-insulating crucible to have a predetermined temperature, and a treatment for coating the inner wall surface of the heat-insulating crucible with a releasing agent.
However, the restoring treatment as described above is applied to the heat-insulating crucible every time when one time of the forming process for the semisolidified metal is completed. The forming operation for the metal formed product is stopped during the period of the restoring treatment. Therefore, the following problem is pointed out. That is, a long period of time is required to perform the forming cycle, and it is impossible to efficiently produce the metal formed product.
Further, the heat-insulating crucible is gripped by a wrist tip of a robot. The semisolidified metal in the heat-insulating crucible is introduced into the injection sleeve which constitutes the forming machine, by performing the rotary action in accordance with the driving action of the robot. Specifically, as shown in FIG. 40, an opening 2 for introducing the slurry is formed on the upper side of an injection sleeve 1 which constitutes a forming machine. A heat-insulating crucible 3, which is gripped by the wrist tip of the robot, is rotated about a center of a rotation axis 4. Accordingly, the semisolidified metal 5 in the heat-insulating crucible 3 is introduced into the injection sleeve 1 through the opening 2.
However, as described above, the heat-insulating crucible 3 is rotated at a constant rotation speed about the center of the rotation axis 4. Therefore, it is extremely difficult to control the falling position of the semisolidified metal 5 in the heat-insulating crucible 3. That is, the angle position for the semisolidified metal 5 to fall from the inside of the heat-insulating crucible 5 tends to vary every time when the introduction is performed. For example, the following situations sometimes occur. That is, the semisolidified metal 5 falls when the heat-insulating crucible 3 is arranged at an angle position P1 (see dashed lines), or the semisolidified metal 5 falls when the heat-insulating crucible 3 is arranged at an angle position P2 (see two-dot chain lines).
As a result, the falling position of the semisolidified metal 5 is diversely varied, and it is difficult to introduce the all amount of the semisolidified metal 5 through the opening 2 into the injection sleeve 1. Further, it is feared that the semisolidified metal 5 remains in the heat-insulating crucible 3. Therefore, a problem is pointed out such that it is impossible to efficiently supply the semisolidified metal 5 to the injection sleeve 1.
On the other hand, the heat-insulating crucible 3 is designed to have a rectangular parallelepiped-shaped configuration corresponding to the shape of the semisolidified metal 5 to be introduced into the injection sleeve 1 which constitutes the forming machine. Therefore, a both-side support hand structure, which supports both ends of the heat-insulating crucible 3 in the longitudinal direction, is usually constructed at the wrist tip of the robot for handling the heat-insulating crucible.
The both-side support hand structure protrudes in a relatively lengthy configuration from the wrist tip of the robot, even when the heat-insulating crucible 3 is not gripped. The interference range of the both-side support hand structure itself is considerably large. For this reason, the following problems are pointed out. That is, it is impossible to move the wrist of the robot in a shortest distance, and it is impossible to shorten the cycle time.
Further, when the semisolidified metal 5 is introduced into the injection sleeve 1, the both-side support hand structure and the forming machine tend to interfere with each other. A problem arises such that the heat-insulating crucible 3 cannot be moved to the position close to the opening 2 of the injection sleeve 1 with ease. Therefore, the semisolidified metal 5 in the heat-insulating crucible 3 must be introduced into the opening 2 at the upward position which is separated from the injection sleeve 1 relatively greatly. A problem arises such that any defective introduction of the semisolidified metal 5 is apt to occur.
On the other hand, as shown in FIG. 41, a plunger 6 is provided at the first end of the injection sleeve 1. The semisolidified metal 5, which has been introduced into the injection sleeve 1, is introduced under pressure into an unillustrated cavity in accordance with the movement of the plunger 6 in the direction of the arrow.
However, in the case of the forming machine described above, the following inconvenience arises. That is, the injection condition for the injection into the cavity is dispersed depending on variations of the sleeve filling rate R and the solidus rate of the semisolidified metal 5. In this case, the volume V of the space portion, which is expressed by the length L of the opening 2 and the inner diameter D of the injection sleeve 1, is V=xcfx80(D/2)2L. The weight Ws, which is obtained when all of the space portion having the volume V is occupied by the semisolidified metal 5, is represented by Ws=2.6V (specific gravity of aluminum molten metal: 2.6). Assuming that the practical casting weight is W, the sleeve filling rate R is defined to be R=(W/Ws)xc3x97100 (%).
In this case, when the sleeve filling rate R is increased, it is feared that an upper portion of the semisolidified metal 5 is spilled out from the opening 2 to the outside of the injection sleeve 1, when the semisolidified metal 5 is injected by applying the pressure with the plunger 6. Further, it is feared that the semisolidified metal 5 overflows from the opening 2, when the semisolidified metal 5 is introduced through the opening 2 into the injection sleeve 1.
On the other hand, when the solidus rate of the semisolidified metal 5 is increased, the semisolidified metal 5 introduced into the injection sleeve 1 overflows from the opening 2. It is feared that when the semisolidified metal 5 is introduced into the opening 2, then the semisolidified metal 5 falls in a transport shape as it is, and the semisolidified metal 5 is not introduced into the opening 2. Therefore, the following problem is pointed out. That is, the injection condition for the injection into the cavity is dispersed, and the product quality is unstable.
When the semisolidified metal 5 is introduced into the injection sleeve 1, a flow like the flow of molten metal tends to be caused. Therefore, it is feared that when the semisolidified metal 5 is injected by applying the pressure with the plunger 6, an upper portion of the semisolidified metal 5 is spilled out from the opening 2 of the injection sleeve 1 to the outside of the injection sleeve 1. Therefore, the following problem is pointed out. That is, the injection condition for the injection into the cavity is dispersed, and the product quality is unstable.
A general object of the present invention is to provide an apparatus for producing a metal formed product, which has a simple structure and which makes it possible to efficiently produce the metal formed product.
A principal object of the present invention is to provide an apparatus for producing a metal formed product, which makes it possible to perform the entire forming operation efficiently and quickly without being affected by a restoring treatment for a vessel.
Another principal object of the present invention is to provide an apparatus for producing a metal formed product, which makes it possible to shorten the cycle time with a simple structure and which makes it possible to effectively avoid the interference with the equipment so that the metal formed product is produced efficiently and highly accurately.
Still another principal object of the present invention is to provide an apparatus for producing a metal formed product, which makes it possible to efficiently obtain the formed product having a stable quality without being affected by the sleeve filling rate and the solidus rate of solid-liquid co-existing metal.
Still another principal object of the present invention is to provide an apparatus and a method for producing a metal formed product, which make it possible to reliably fill a cavity with solid-liquid co-existing metal and efficiently obtain the formed product having a stable quality.
Still another principal object of the present invention is to provide a method for producing a metal formed product, which makes it possible to introduce solid-liquid co-existing metal from a vessel into an injection sleeve quickly and reliably.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.